------Program code: DO-090102-03210 (what's this?)
Source: CCTV.com
01-02-2009 16:18
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On the top and bottom of the cantilever, firm steel beams connect with the towers to ‘hold’ the cantilever.
As the main building has a ring-shaped structure, the towers to the ends of the cantilever and the turning at the bottom work together to form a conjunct weighted system. They both affect and support one another make the structure possible.
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In the spring of 2003, in the Office of Metropolitan Affairs in Rotterdam, Holland, local designers and their partners from China - engineers of the Shanghai Huadong Architectural Design Institute - began to further develop their plan. They carried out various kinds of tests, analyses and simulations. The most important trial was the earthquake resistance test.
According to historical data, Beijing is located in the Huabei area earthquake belt, an active belt where around 200 earthquakes of magnitude 4 or above have occurred. The most severe was the 1679 earthquake in Pinggu district, which was force 8.
The main building of the CCTV new site had to go through strict tests regarding its ability to resist earthquakes.
The structural engineers built a three-storey high (1: 35) model and then set the model on a shaking platform to observe its response to earthquakes of different magnitudes. By doing this they were able to locate and reinforce weak points in the structure.
As the test result shows, the main building of the CCTV new site has a fortified fracture resistance against earthquakes of around 8.49, a level that exceeds the standard of 8 set by the Beijing municipal government.
In December 2007， construction of the CCTV new site entered the most critical stage – closure of the cantilever at the top of the building.
However, due to obvious differences in temperature between day and the night, the length of the steel beams in the cantilever would vary slightly in different time periods, and this would affect the accuracy of the final closure.
Koolhaas had been watching the development of the project closely. The news from the construction site made him feel nervous.
